/*
 * InputNode.java July 2006
 *
 * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.stream;

/**
 * The <code>InputNode</code> object represents an iterator for the
 * elements within an element. This allows the input node object to
 * become a self contained iterator for an element and its children.
 * Each child taken from the input node object, is itself an input
 * node, and can be used to explore its sub elements without having
 * any affect on its outer elements.
 *
 * @author Niall Gallagher
 */
public interface InputNode extends Node {

    /**
     * This method is used to determine if this node is the root
     * node for the XML document. The root node is the first node
     * in the document and has no sibling nodes. This is false
     * if the node has a parent node or a sibling node.
     *
     * @return true if this is the root node within the document
     */
    boolean isRoot();

    /**
     * This is used to determine if this node is an element. This
     * allows users of the framework to make a distinction between
     * nodes that represent attributes and nodes that represent
     * elements. This is particularly useful given that attribute
     * nodes do not maintain a node map of attributes.
     *
     * @return this returns true if the node is an element node
     */
    boolean isElement();

    /**
     * This is used to acquire the namespace prefix for the node.
     * If there is no namespace prefix for the node then this will
     * return null. Acquiring the prefix enables the qualification
     * of the node to be determined. It also allows nodes to be
     * grouped by its prefix and allows group operations.
     *
     * @return this returns the prefix associated with this node
     */
    String getPrefix();

    /**
     * This allows the namespace reference URI to be determined.
     * A reference is a globally unique string that allows the
     * node to be identified. Typically the reference will be a URI
     * but it can be any unique string used to identify the node.
     * This allows the node to be identified within the namespace.
     *
     * @return this returns the associated namespace reference URI
     */
    String getReference();


    /**
     * Provides an attribute from the element represented. If an
     * attribute for the specified name does not exist within the
     * element represented then this method will return null.
     *
     * @param name this is the name of the attribute to retrieve
     * @return this returns the value for the named attribute
     */
    InputNode getAttribute(String name);

    /**
     * This returns a map of the attributes contained within the
     * element. If no elements exist within the element then this
     * returns an empty map.
     *
     * @return this returns a map of attributes for the element
     */
    NodeMap<InputNode> getAttributes();

    /**
     * This is used to acquire the <code>Node</code> that is the
     * parent of this node. This will return the node that is
     * the direct parent of this node and allows for siblings to
     * make use of nodes with their parents if required.
     *
     * @return this returns the parent node for this node
     */
    @Override
    InputNode getParent();

    /**
     * This is used to return the source object for this node. This
     * is used primarily as a means to determine which XML provider
     * is parsing the source document and producing the nodes. It
     * is useful to be able to determine the XML provider like this.
     *
     * @return this returns the source of this input node
     */
    Object getSource();

    /**
     * This returns the next child element within this element if
     * one exists. If all children have been read, or if there are
     * no child elements for this element then this returns null.
     *
     * @return this returns an input node for the next child
     * @throws Exception thrown if there was a parse error
     */
    InputNode getNext() throws Exception;

    /**
     * This returns the next child in this element if that child
     * has the name provided. If the next child element in this
     * node does not have the name given then null is returned.
     *
     * @param name this is the name of the next child element
     * @return the next element if it has the name specified
     * @throws Exception thrown if there was a parse error
     */
    InputNode getNext(String name) throws Exception;

    /**
     * This method is used to skip all child elements from this
     * element. This allows elements to be effectively skipped such
     * that when parsing a document if an element is not required
     * then that element can be completely removed from the XML.
     *
     * @throws Exception thrown if there was a parse error
     */
    void skip() throws Exception;

    /**
     * This is used to determine if this input node is empty. An
     * empty node is one with no attributes or children. This can
     * be used to determine if a given node represents an empty
     * entity, with which no extra data can be extracted.
     *
     * @return this returns true if the node is an empty element
     * @throws Exception thrown if there was a parse error
     */
    boolean isEmpty() throws Exception;


}
